The invention relates to a writing implement comprising a housing, a writing cartridge movably arranged in the housing, and a control unit form moving the writing cartridge between a first position in which the cartridge tip is extended out of the housing for writing, and a second position in which the writing cartridge is retracted within the housing, wherein in the first position the writing implement has an overall length suitable for writing and in the second position the writing implement is shortened.
A writing implement of this general type is disclosed in EP 402,558A. This writing implement comprises a housing, a depressor configured as an extension of the housing, and a control unit with a first switching cam by which the writing cartridge can be extended into its first writing position or moved into the housing in its second retracted position. The control unit further comprises a second switching cam that interacts with the depressor. To push the writing cartridge out of the housing into the writing position, the depressor must be pulled backward out of the housing. This xe2x80x9cpulling motionxe2x80x9d to displace the writing cartridge forward into its writing position makes handling more difficult, especially since this motion is in inverse direction of the desired forward motion of the writing cartridge out of the housing toward the front. In the writing position, the writing cartridge is secured against being pushed back into the housing by a pin that engages a rearward pointing part of the first cam. To shorten the writing implement and move the writing cartridge into the second retracted position, the depressor is pushed in the direction of the housing, i.e., against the aforementioned xe2x80x9cpulling motion.xe2x80x9d In its telescoped, short position, the depressor is not fixed relative to the housing, so that when the writing implement is taken out of a holder, for example, the depressor could be accidentally pulled backward and the writing cartridge pushed forward out of the housing. The writing implement is difficult to handle in that to set the writing position, a user must hold the housing with one hand to be able to pull the depressor backward out of the housing with the other hand.
EP 968,843A furthermore discloses a variable writing implement whose rear housing part including a depressor is coupled to the front housing part via a gear-type connection with racks and an engaging pinion. To extend the shortened writing implement and push out the writing cartridge, the depressor together with the rear housing part must be pulled out of the front housing part.
Furthermore, U.S. Pat. No. 2,627,843 discloses a writing instrument whose housing is made of two parts that can be telescoped into one another. Disposed in the front part is a writing cartridge, which can be axially displaced by a control unit in such a way that in a first position, the tip of the cartridge protrudes from the front part for writing and in a second position, the tip of the cartridge is retracted into the front part. The control unit includes an axially displaceable and partially rotatable first sleeve in which the writing cartridge is inserted and from which the writing cartridge can be removed when required after removal of a housing tip. A pin of the front part engages a short spiral groove in the outer surface of the rotatable control sleeve, so that the first sleeve is axially displaced as it is rotated and the writing cartridge is thereby displaced into the first or the second position. The interior of the rear part of the housing contains an additional sleeve with an axial slot in which a projection provided on the rear end of the front part engages. This additional sleeve of the rear part further has an axially inwardly pointing projection that engages a second long spiral groove of the control sleeve of the front part. When the front part and the rear part are telescoped, the first sleeve is rotated by the projection of the additional sleeve, which is non-rotatably arranged in the rear part and engages the long spiral groove. In cooperation with the short front spiral groove, the first sleeve is pushed axially rearward and the tip of the cartridge is thus retracted into the housing, its second position. In this second position, the two housing parts are telescoped into one another so that the total length of the housing is shorter overall. To bring the writing cartridge or the writing point into its first or writing position, the front part of the housing and the rear part of the housing are axially pulled apart. The above-described functions then proceed in the reverse direction and the first sleeve, including the writing cartridge, is axially displaced forward and the tip of the cartridge is pushed out of the housing into the first or writing position. After the two housing parts have been fully pulled apart, the writing instrument has its maximum length. The writing instrument is difficult to handle in that both hands are required to pull it apart to adjust the writing position and to telescope the two housing parts in an opposite movement to adjust the second position. Furthermore, there is no mutual locking device of the two housing parts either in the writing position or in the second position. If the two housing parts are accidentally moved relative to one another, proper writing can be affected or the tip of the cartridge can be moved out of its second position, with the risk that articles of clothing or the like may be stained by the writing agent.
It is therefore an object of the present invention to provide an improved writing implement of the aforedescribed type.
Another object of the invention is to provide a writing implement without major structural modification which will exhibit improved handling.
A further object of the invention is to provide a writing implement in which the writing cartridge can be extended into its functional or writing position and the writing implement itself simultaneously lengthened with a single manual action.
An additional object is to provide a writing implement which is operable with one hand and is extendable into the size that is suitable for writing with the same type of movement that is required to shorten it and to retract the writing cartridge into its standby position.
Yet another object of the invention is to provide a writing implement in which the two positions of the writing cartridge are reliably defined and any accidental actuation is reliably avoided.
These and other objects are achieved in accordance with the present invention by providing a writing implement comprising a housing, a writing cartridge movably arranged in said housing, a depressor configured as an extension of the housing, and a control unit having a first switching cam for displacing the writing cartridge between a first position in which the cartridge tip is extended out of the housing for writing, and a second position in which the writing cartridge is retracted within the housing, wherein the writing implement in the first position has an overall length suitable for writing and in the second position is shortened; wherein the control unit has a second switching cam which interacts with the depressor; wherein the depressor can be actuated in the same pressing direction to displace the writing cartridge both into the first position and into the second position, wherein the second switching cam is configured to fix the depressor in the second, telescoped and shorted position, and wherein the second switching cam is configured in such a way that, starting from the telescoped position, the depressor is unlocked when the depressor is actuated in the pressing direction and can be extended out of a rear end of the housing into the first position.
The writing implement according to the invention is distinguished by its functionally reliable design and its simple handling. The two positions are actuated and defined exclusively by a pressing motion. The writing implement has a control unit that is actuated by means of a depressor so that the writing cartridge can be optionally brought into its writing position or into its retracted position. Synchronously with the corresponding actuation, the writing implement is lengthened to the size adapted for writing or shortened for stowing or storing. This creates a small writing implement that is suitable for stowing and storing in small containers, pockets, particularly trouser pockets, notepads, small pocket calendars, small planners or the like.
The control unit comprises a cam element with two preferably inline switching cams. These cams are arranged in such a way that the writing cartridge can be brought into the writing position or the retracted position by means of the first switching cam while the depressor, which is configured as an extension, is displaced out of the housing or retracted into the short position by means of the second switching cam. The first switching cam for the writing cartridge is preferably configured in such a way, and especially as a heart-shaped cam, to ensure that the writing cartridge is reliably blocked in the two possible positions. The switching cam for the depressor is preferably configured as an unlocking control cam.
The depressor, starting from the locked position when the writing implement is shortened, is extended into its lengthened position after unlocking, particularly under the action of a spring force. Advantageously, the cam element is rotatable and axially displaceable inside the housing and, depending on its position, can either prevent the depressor from being extended or can release and unlock it.
Further advantageous aspects and preferred features and embodiments of the invention are described in additional detail in the following.